According to allegations raised in a wrongful death lawsuit filed against GlaxoSmithKline, the drug maker failed to provide adequate warnings about the potential side effects of Zofran for unborn children, indicating that use of the popular anti-nausea drug to combat morning sickness caused Michigan couple’s twin children to develop severe deformities and birth defects.

The complaint (PDF) was filed last week in the U.S. District Court for the District of Massachusetts by Holly L. Estapa and Martin W. Hauger, alleging that one of their children died during a caesarian section due to numerous birth defects and the other survived, but has been left with long-term health consequences.

Estapa indicates that she was prescribed Zofran during pregnancy, which allegedly caused birth defects for her minor children, identified by the initials B.A. and B.B. in the complaint.

Zofran is approved for use to treat nausea and vomiting associated with chemotherapy and surgery, but the medication is widely prescribed off label for pregnant women suffering morning sickness. The case raises similar allegations to those raised in a number of other Zofran birth defect lawsuits, alleging that GlaxoSmithKline failed to adequately warn women and the medical community about the risk the medication may pose for unborn children.

According to the wrongful death lawsuit, B.A. developed heart malformations and placental pathology from exposure to Zofran during pregnacy, ultimately causing the child’s death due to heart failure and intrauterine fetal demise. B.A. was diagnosed as having an enlarged heart with dilation of the right atria, right ventricle and pulmonary artery, restrictive foramen ovale, subaortic ventricular septal defect, a narrowed aortic valve, underdeveloped left atrium and left ventricle, and other defects as well that impacted the kidneys, liver, pancreas and adrenal glands.

B.B., who survived, was diagnosed with an anterior muscular ventricle septal defect and other heart problems from Zofran, which may require future surgeries and medical treatment, as well as monitoring.

The lawsuit indicates there was no family history of such birth defects. However, it notes that GlaxoSmithKline knew such defects were associated with Zofran as early as the 1980s.

“In the 1980s and 1990s, GSK conducted animal studies which revealed evidence of toxicity, intrauterine deaths and malformations in offspring, and further showed that Zofran’s active ingredient transferred through the placental barrier of pregnant mammals to fetuses,” the lawsuit indicates. “A later study conducted in humans confirmed that ingested Zofran readily crossed the human placenta barrier and exposed fetuses to substantial concentrations. GSK did not disclose this material information to pregnant women or their physicians.”

The Zofran birth defect litigation has rapidly emerged over the past two years, as more and more families learned about the link between the anti-nausea drug to their children’s congenital malformations, including heart problems, cleft lip, cleft palate and other congenital malformations.

The complaint filed by Estapa and Hauger will be transferred into a federal multidistrict litigation (MDL) established for all Zofran cases pending throughout the federal court system, which are currently centralized before U.S. District Judge Dennis Saylor in the District of Massachusetts.

As part of the coordinated proceedings, a small group of cases will be prepared for early trial dates to help the parties gauge how juries may respond to certain evidence and testimony that is likely to be repeated throughout a number of cases. If GlaxoSmithKline fails to reach Zofran settlements to resolve birth defect cases following these early “bellwether” trials, each of the individual lawsuits included in the MDL may end up being remanded back to U.S. District Courts nationwide for separate trial dates.